310 THE RABBIT 



the anterior dorsal portion of the os innominatum and the anterior 

 and greater portion (about half) of the acetabulum. 



(b) The ischium, forming the posterior dorsal portion of the os innominatum 



and the posterior third of the acetabulum. The two ischia unite 

 ventrally, forming the posterior part of the pelvic symphysis, the 

 anterior and greater part being pubic. 



(c) The pubis, the ventral portion of the os innominatum. The pubes 



unite ventrally in the middle line to form the pubic symphysis, and 

 join the ischia to form the obturator foramen of each side. The pubis 

 completes the acetabulum below. 

 Make a sketch of the pelvic girdle. {See Fig. 104,' page 308.) 



4. The Hind-limb. 



Carefully clean the left hind-limb, and note the following parts : — 



(a) The femur or thigh bone, a long bone with a cylindrical shaft and en- 

 larged extremities. The prominent head articulating with the aceta- 

 bulum forms the hip-joint. External to the head, and forming the 

 anterior extremity of the shaft, is a large process, the great trochanter. 

 Below the head and on the inner side of the shaft is the lesser tro- 

 chanter ; and opposite it, on the outer side, is the third trochanter. 

 The trochanters serve for the attachment of the muscles of the leg. 

 The lower extremity has two large condyles (with a groove between) 

 for articulation with the tibia. 



(6) The small knee-pan or patella, opposite the knee-joint, situated in the 

 front groove on the lower end of the femur. It is a sesamoid, bone in 

 the extensor muscle tendon. 



(c) The tibia, a stout and straight long bone, articulating at its upper and 

 triangular end with the femur, by two facets, and at its lower end with 

 the astragalus. 



{d) The fibula, a slender bone, articulating at its upper end with the outer 

 surface of the head of the tibia. Its distal portion is fused with the 

 tibia and articulates (at the end) with the calcaneum. The inner 

 tibia and outer fibula constitute the leg, lower leg or shank. 



(e) The tarsus or ankle, consisting of two rows of tarsal bones : — 



(i) The proximal row is composed of the astragalus on the inner 

 side, and the calcaneum (os calcis or fibulare) on the outer 

 side. The calcaneum is produced into the large calcaneal 

 process which forms the heel, and on which the tendo Achillis 

 is inserted. These two tarsals articulate with the tibia-fibula, 

 (ii) The distal row is composed of three bones, viz. the inner meso- 

 cuneiform supporting the second metatarsal, the median 

 ecto-cuneiform supporting the third metatarsal, and the outer 

 cuboid articulating with the calcaneum and supporting the 

 fourth and fifth metatarsals. Corresponding to the centrale 

 of the carpus there is a navicular, between the two rows and 

 in front of the astragalus, and articulating with the meso- 

 cuneifoi-m and ecto-cuneiform. 



